Subject: [Sip] GRUU: problem with description of solution to edge-router problem

From: "Dale R. Worley" <[email-masked]>
Date: Tue, 08 Nov 2005 17:26:23 -0500

I've been trying to fully understand the solution to the "edge router"
problem that is described in section 8.4.2 of draft-ietf-sip-gruu-06.
One component of the solution is described at the top of page 25:

   Similarly, if a request arrives from the client towards the home
   proxy, the edge proxy would look at the identity of the sender of the
   request.  If the proxy knows that it is placing itself on the Path
   for registrations from that AOR, and the request contains a Supported
   header field with the value "gruu", the edge proxy would insert a
   Record-Route into the request, and then remove it in the response.

I believe that this description is incorrect, in fact reversed from the
behavior that is desired.  I've charted the message flows for dialog-
establishing messages in the edge-router situation, and the route-sets
that we want established at the ends of the dialog.  From the route-
sets, one can determine the manipulations that the edge router must
perform on the request and response.

The message flows are in an attachment to this message.

>From the message flow, it seems to me that the above quoted paragraph is
incorrect, and should be written as

   Similarly, if a request arrives from the client towards the home
   proxy, the edge proxy would look at the identity of the sender of the
   request.  If the proxy knows that it is placing itself on the Path
   for registrations from that AOR, and the request contains a Supported
   header field with the value "gruu", the edge proxy would not insert a
   Record-Route into the request, but would rather insert it into the response.

I fear that I may be overlooking something here and making a fool of
myself, but I've checked this over, and I think that this is a bug in
the text of the I-D.

Dale

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